Gelatin is a proteinaceous material derived from collagen by hydrolytic action which is produced at a purity suitable for edible consumption. Gelatin is soluble or dispersible in hot water, and can swell to take-up about 5-10 times its own weight of water to form a gel. It is useful for the preparation of food products, such as desserts, photochemical tissue for rotogravure printing, subbings for photographic film, sizing for textiles and papers, and the like. With the exception of its use in adhesives, where gelatin may comprise about 30 to about 50 weight percent of the product composition, gelatin is typically used at a concentration of about 0.25 to about 25 weight percent of an aqueous composition.
In some uses, the gelatin composition is used in relatively large, gelled blocks, as in a dessert, while in other uses, it is utilized as an extremely thin, gelled film, as in a photographic subbing. When used in adhesives, the gelatin composition is normally a liquid at the time of ultimate use.
Gelled food products, such as desserts, typically contain about 1 to about 3.5 weight percent gelatin along with various other ingredients such as one or more food acids for tartness, sweetener and flavorant. Non-dessert gelled food products, such as aspics, also contain about 1 to about 3.5 weight percent gelatin with flavor containing materials, such as tomato juice, beef broth, or clam broth, and usually common table salt. These compositions typically gel at temperatures less than about 70.degree. F. (about 20.degree. C.), and are usually refrigerated at temperatures of about 50.degree.-55.degree. F. (about 10.degree.-13.degree. C.) to initiate gelation. Other gelatin-containing food products such as marshmallows, head cheese, canned hams and ice milks generally contain from about 0.25 to about 15 weight percent gelatin, based upon the weight of the water present, along with the usually used flavorants such as sweeteners and spices.
A difficulty arising from the use of gelatin compositions stems from the fact that dry gelatin is not readily soluble in cold or tepid water. Rather, the dry gelatin must be heated and agitated with water to a temperature of about 50.degree.-60.degree. C. so that it will dissolve.
Concentrated gelatin solutions containing about 10 to about 60 weight percent gelatin can be made, but these solutions gel at temperatures above ambient room temperature, and once gelled, they must be reheated and agitated during the dilution step as gelled gelatin compositions are not soluble in cold or tepid water. It would therefore be advantageous if a storage stable, readily dilutable, concentrated, liquid gelatin solution could be prepared which would need no heating step for its dilution and consequently also need less agitation and cooling to be in a usable condition.
The use of liquefying agents or lyotropic agents in adhesives containing relatively high concentrations of hydrolyzed collagen; i.e., about 30-50 weight percent, has been known for sometime. For example, U.S. Pat. No. 1,394,654, No. 1,844,679, No. 1,873,580, No. 1,950,483, No. 2,048,499, No. 2,126,305 and No. 2,658,001 teach that thiourea, urea, biuret, alkali metal nitrates, dextrines, infusorial or diatomaceous earth, alkaline earth salicylates, ethyl alcohol, glycerol, furfuryl or tetrahydrofurfuryl alcohols, 2-methoxy methanol, thiocyanate salts and the like are useful to lower the gelling temperature of various hydrolyzed collagen-containing compositions. In addition, U.S. Pat. No. 2,413,815, states that boiling a gelatin solution with phosphoric acid at a composition pH value of less than 5.7, followed by neutralization with calcium carbonate to a pH value between 5.7 and 5.9 and filtration, leads to a composition which may contain more than 20 weight percent gelatin and still remain liquid down to the temperature at which the solvent congeals.
A more recent patent, U.S. Pat. No. 4,224,353, acknowledging the known lyotropic effect of acid pH values upon aqueous gelatin solutions, teaches that gellable aqueous gelatin-containing dessert starter compositions can be prepared using an acid as the lyotropic agent. The syrups of that invention are said to be suitably prepared containing from about 5 to 40 percent gelatin, from about 5 to about 40 percent acid and from about 20 to 90 percent water, with the acid present at about 30-200 percent of the weight of the gelatin. The dessert starter compositions gel to form the final dessert products when they are mixed with sufficient buffer to raise the pH of the dessert composition to about 3.6 to 4.6. Water is also be added to achieve the desired gelatin concentration of ingredients.
The compositions of the above patent are, however, said to deteriorate on storage at room temperature due to hydrolysis of the gelatin protein under acid conditions. Those gelatin-containing syrups are therefore preferably stored and sold in a refrigerated or frozen form along with the neutralizing buffer salts.
Aside from the lack of convenience of the products of the above patent due to their storage under refrigerated conditions, the food product made using the proportions of ingredients set out in its sole Example was found to have a metallic taste. It is presumed that the taste so found arose from the relatively high amount of buffer salt needed to raise the composition to the proper pH value for gelling. That product also contains a relatively high sugar content, also presumably to help mask the metallic flavor.
None of the above-described art teaches or suggests that room temperature storage stable, ungelled gelatin-containing concentrates can be prepared using a non-acid lyotrope, and then diluted with water to form gelled gelatin-containing food products which gel at temperatures above the gelling temperature of the concentrate, and at temperatures similar to product compositions containing the same amount of gelatin and no lyotropic agent, as is taught hereinbelow.